Wind Farm

This case is a large-eddy simulation of a wind farm under neutral stability conditions. The simulation requires 3 steps: 1) running a precursor atmospheric boundary layer simulation, 2) sampling the data from the boundaries, and 3) running the wind farm simulation with inflow/outflow boundary conditions.

This examples guides the user through all these steps.

Case 1: Precursor simulation

This example follows the same procedure as Atmospheric Boundary Layer - Neutral. The only difference is that now, the boundary data is sampled.

1. Load the appropriate Nalu environment. This requires loading the libraries and Python environment as described in Setting up the environment. For users on Peregrine the function defined in Initial Setup should suffice:

   nalu_env
   

2. Go to the directory where the case is:

   cd nalu-wind/examples/wind_farm/case1/
   

3. Modify the setup.yaml file to include all the necessary simulation parameters.

4. Run the executable and provide the setup.yaml file as input:

   ../../nalu_input_fileX -s setup.yaml
   

5. Generate the mesh:

   ../abl_mesh -i case_1_precursor_preprocess.yaml
   

6. Generate the initial condition:

   ../nalu_preprocess -i case_1_precursor_preprocess.yaml
   

7. Run the nalu executable:

   mpirun -np 8 ../naluX -i case_1_precursor_simulation.yaml
   

   In this example 8 processors are used, but any number of processors could be used. Target 50K elements per core for choosing number of MPI cores.

Case 2: Sampling boundary data

Now, a simulation for sampling the boundary data is performed. This is the same as the previous simulation, but with 2 changes: 1) Data sampling from the boundary conditions. 2) Different time interval

1. Load the appropriate Nalu environment. This requires loading the libraries and Python environment as described in Setting up the environment. For users on Peregrine the function defined in Initial Setup should suffice:

   nalu_env
   

2. Go to the directory where the case is:

   cd nalu-wind/examples/wind_farm/case2
   

3. Modify the setup.yaml file to include all the necessary simulation parameters.

4. Run the executable and provide the case_2_setup_abl_precursor_boundary_data.yaml file as input:

   ../../nalu_input_fileX -s setup.yaml
   

5. Generate the boundary data to sample:

   ../nalu_preprocess -i case_2_boundary_data_preprocess.yaml
   

6. Run the nalu executable:

   mpirun -np 8 ../naluX -i case_2_abl_precursor_boundary_data.yaml
   

   In this example 8 processors are used, but any number of processors could be used. Target 50K elements per core for choosing number of MPI cores.

Case 3: Wind farm simulation

The last part is the wind farm simulation. In this example, the simulation is run using the same resolution as the precursor. However, it is possible to perform local refinement near the turbines. Full instructions are provided in wind-utils.

1. Load the appropriate Nalu environment. This requires loading the libraries and Python environment as described in Setting up the environment. For users on Peregrine the function defined in Initial Setup should suffice:

   nalu_env
   

2. Go to the directory where the case is:

   cd nalu-wind/examples/wind_farm/case3
   

3. Modify the setup.yaml file to include all the necessary simulation parameters.

4. Run the executable and provide the setup.yaml file as input:

   ../../nalu_input_fileX -s setup.yaml
   

5. Run the nalu executable:

   mpirun -np 8 ../naluX -i case_3_wind_farm.yaml
   

   In this example 8 processors are used, but any number of processors could be used. Target 50K elements per core for choosing number of MPI cores.

Post-processing

The data generated by this example can be post-processed using the same scripts provided in Atmospheric Boundary Layer - Neutral and Actuator Line Model in Uniform Inflow.